Anharmonic Effects in Single-Walled Carbon Nanotubes Analyzed through Low-Temperature Raman Imaging
Anharmonic Effects in Single-Walled Carbon Nanotubes Analyzed through Low-Temperature Raman Imaging
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DOI：
10.1021/acs.jpcc.0c00416
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发表时间：
2020-03
影响因子：
3.7
通讯作者：
T. Umakoshi;M. Taniguchi;P. Verma
中科院分区：
文献类型：
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作者：
T. Umakoshi;M. Taniguchi;P. Verma
单壁碳纳米管(SWCNTs)的高导热性能使其在潜在的热器件中得到了广泛的应用。在这里，我们使用自制的小型低温恒温器系统，通过依赖温度的拉曼成像，研究了声子相互作用引起的单壁碳纳米管束的非谐效应。低温恒温器系统足够小，可以安装在压电式扫描仪上，以抑制热漂移，从而在不同温度下进行拉曼成像。我们获得了几束单壁碳纳米管束在不同温度下的拉曼光谱图像，其空间分辨率为几百纳米。我们发现，不同束的拉曼峰强度、峰位移和拉曼峰宽随温度变化不同。考虑到原子力显微镜观察到的样品形貌，进一步解释了样品的温度依赖性，其中束效应似乎对非谐性起着重要的作用。基于空间分辨成像的温度相关拉曼分析将成为研究先进碳纳米材料的非谐效应以及实现未来热器件热学性质的原位可视化的有力工具。
The high thermal conductivity of single-walled carbon nanotubes (SWCNTs) has gained much attention for their applications in potential thermal devices. Here, we investigate anharmonic effects, originated from phonon interactions, of SWCNT bundles by temperature dependent Raman imaging using our home-built mini cryostat system. The cryostat system is small enough to be mounted on a piezo scanner that suppresses thermal drift, enabling Raman imaging at different temperatures. We obtained Raman spectral images of several SWCNT bundles with a spatial resolution of a few hundred nanometers at different temperatures. We found that different bundles show different temperature dependences of Raman peak intensity, shift, and width. The temperature dependence was further elucidated by considering the sample topography observed by atomic force microscopy, where bundle effects seem to play an important role to influence the anharmonicity. The temperature-dependent Raman analysis based on spatially resolved imaging will be a powerful tool to investigate anharmonic effects of advanced carbon nanomaterials as well as to realize in situ visualization of thermal properties for future thermal devices.